[FEATURE] Cowork / Code sidebar task names should follow conversation language (not default to English)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When using Claude Desktop in Cowork or Code mode, task/session names generated in the left sidebar are almost always in English, even when the entire conversation is conducted in Japanese (or other non-English languages).

Example:

• User prompt (in Japanese): 「小型無線機2機種を比較して」
• Generated task name (in English): "Compare two radio equipment models"

This is inconsistent and disruptive for non-English users who rely on the sidebar to navigate and manage their tasks.

Expected Behavior:
The auto-generated task/session name should follow the language of the conversation. If the user interacts in Japanese, the task name should be generated in Japanese.

Proposed Solution

Auto-detect the conversation language and generate task/session names accordingly. Alternatively, add a language preference setting (e.g., in /config or settings.json) that controls the language used for UI-generated labels such as task names.

Alternative Solutions

Adding explicit instructions at the start of each task (e.g., "タスク名は必ず日本語で生成してください") — but this requires manual repetition every session. CLAUDE.md language instructions have minimal effect on task name generation, as the model's training pattern dominates (similar to issue #27051).

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

Related issues: #7233, #27051, #28451

This affects all non-English speaking users of Cowork and Code, particularly those in Japanese, Korean, Chinese, and other CJK language markets — which represent a significant and growing user base for Anthropic.